1. Field of the Invention
The requirement to refill containers to a prescribed level occurs frequently, and calls out for a valve that is low cost, highly reliable, efficient in both preventing flow when no flow is indicated, and permitting a large flow when flow is desired. By virtue of their many parts, valves often fail because vibrations cause the parts to come apart, or because friction between the moving parts causes wear and ultimately a failure in the valve's capability to prevent flow in the "off" position. In addition, valves which are designed to remain sealed, with the exception of a single exit orifice, require a seal of some type in order to interface the operating knob or lever to the valve, creating an opportunity for leaks or requiring maintenance when leaks develop. In addition, valves that use a sphere which mates with a concave surface of the same radius often develop leaks due to small contaminants which may become trapped between the sphere and the seat, thereby scratching either the sphere or the seat, and producing a leak in the valve's sealing mechanism. The invention solves these problems by virtue of a simple one part housing that is inexpensive to manufacture and highly reliable, no seals to interface the operating lever to the valve, a highly efficient two stage mechanism when the valve is in the off position, and a high flow performance when the valve is in the open position. Such valves are often referred to as "filling" valves, or "float" valves.
2. Description of Prior Art
The subject invention solves the problem of creating a valve that is not susceptible to leaks, even when used with water supplies that have impurities. Previous inventions taught some, but not all, of the features of this invention.
U.S. Pat. No. 4,462,417 for a valve assembly presented a solution to the problem of using a sphere mating with a cylindrical seat, in the application of a propane or LPG application, in which the material passing through the valve is a gas, and does not contain impurities. If impurities were to pass through this valve, as the valve were closing, they would become trapped between the sphere and the cylindrical seat, creating an indentation in either the sphere or the cylinder if the material had a hardness sufficient to create such an indentation, and would thereby create a leak in the sealing mechanism.
U.S. Pat. No. 4,873,832 for a liquid level control for a cryogenic fluid utilized a sphere which, when in the sealing position to prevent flow, formed a seal by making contact with a circular opening having a diameter smaller than that of the sphere, when the actuating lever permits the sphere to completely contact the bore through which fluid passes in the valve's open state. The valve operates with ultra pure fluids, in a semiconductor manufacturing environment, and would not operate effectively in the presence of any contaminants, which would become lodged in the valve seat mechanism, creating a leak and destroying the ability of the valve to maintain the desired level of fluid.
U.S. Pat. No. 3,269,406 is a valve that is intended to operate with water, or other fluids that might contain contaminants. Due to the design, which places pressure on the sphere from below, through force generated by a float exerted through a lever, the valve will inadvertently permit flow whenever the inlet pressure exceeds the force generated by the float, leveraged through a rod or pawl intended to press the sphere firmly into a funnel like seat. The design will leak whenever a contaminant, for example a grain of sand, lodges between the sphere and the funnel shaped valve seat.
U.S. Pat. No. 1,619,431 is a valve that utilizes a rubber O-Ring in conjunction with a metal seat. This valve operates in a vertical, rather than a horizontal position, and as a result contaminants like sand will tend to collect on the O-Ring at the lowest position, thereby wearing at the O-Ring in the same place, and thereby reducing the reliability of the valve. As disclosed, this invention provides for the sphere to make contact with a seat on both sides of the O-Ring, thereby permitting a contaminant to be trapped between two hard surfaces. If the contaminant is trapped between the sphere and the hard seat of the valve, the valve will fail to inhibit the flow of a fluid when in the "off" position. This invention also requires a positive pressure from the inlet in order to seal, and under very low pressures or intermittent negative pressures will leak.
U.S. Pat. No. 5,645,105 is for a tank filling shut-off valve in which a sphere makes contact with an O-Ring when the entire valve assembly rises to a point that removes an affixed rod from blocking the sphere's ability to fall into place and form a seal with the O-Ring. The design depends on the weight of the valve assembly to be sufficient to overcome the pressure that the inlet fluid exerts on the sphere. In the event that the inlet pressure is high, the valve may fail to open until the pressure drops low enough to permit the rod to force the sphere upward, thereby permitting a flow of fluid through the valve.
U.S. Pat. No. 766,416 is for a valve that serves a hog waterer, and employs a cylindrical seat of a material that conforms with the sphere pressed against it by gravity supplemented by the force of a second sphere, whose purpose is to provide an additional pressure on the lower sphere, and to thereby improve the seal. Under high pressure, this design is susceptible to leaks around the sealing mechanism, which depends on the deforming material holding shape against high pressures.
U.S. Pat. No. 1,623,374 is for a valve having a sphere that rests in a concave seat containing a hole through which water is discharged. The valve depends on a metal to metal contact for a seal, and depends on gravity to force the sphere against the pressure of water flowing below the sphere. Under very high flow situations, the valve may fail to close, due to the high flow tending to press the sphere into the housing provided to hold the sphere when the valve is in the open position.
U.S. Pat. No. 1,097,476 is for a valve which operates with a deformable seal, and under high pressures would leak. In the vertical rendition, a very high pressure and resulting flow could force the sphere to remain in the open position, since the flow does not reinforce the sphere's being forced to seal the valve closed. In this instance, the valve could fail to close when the water level reached the desired level, thereby causing an overflow and a failure of the system controlled by the valve.
U.S. Pat. No. 1,551,808 is for a valve made of an inverted "U" shaped housing, with a plug threaded from the top, and a sphere made of rubber or some other compressible material. Under very high pressures, a compressible sphere could be forced through the outlet opening, causing the valve to fail. A compressible sphere would also degrade with time, necessitating a repair or replacement of the valve. Such a repair is contemplated by the threaded plug in the invention.
The prior art does not solve the problem of providing a valve that is secure in the closed position under both zero and high pressure, tolerant of impurities, simple to manufacture, and with an ease of configuration and installation.